Assigning separate branded entry points or domain names for each environment and linking them to the respective stages in the backend service with a base path that indicates the environment ensures that each entry point maintains a connection to the appropriate stage. Moreover, it provides a clean and structured approach to handling environment-specific endpoints, achieving the requirement for a cohesive but clearly demarcated set of entry points for each service stage. The other options either merge environments under a single entry point, leading to ambiguity, or do not make use of domain names which is less ideal for a branded experience.